Drilling operations used to drill oil and gas wells and the like face a number of challenges. A particular problem arises because the drilling operation take place underground such that it is difficult to obtain an accurate view of what is going on during the drilling process. It can therefore be difficult for the operator to be able to make good decisions to control the drilling process.
Drilling operations typically take place according to a drilling plan that is designed to place the well in the underground formations of interest. This plan will provide an intended well trajectory that the driller tries to follow. The plan will be based on sub-surface information obtained from the surface (such as by seismic surveying) or offset information from adjacent wells.
As the drilling operation proceeds, measurements are taken that can be used to estimate the trajectory of the well, and the position of the drilling equipment. Such measurements can include direction and inclination measurements made by the drilling equipment (surveys or current positions of the well), and formation measurements such as resistivity measurements that provide the information on the formation surrounding the sensor. However, such measurements do not inherently indicate the future trajectory of the well.
A number of existing techniques allow imaging of the well after drilling and association with subsurface formation properties. Schlumberger's WellEye and EcoView products and services allow imaging of such cases. There are a number of existing techniques for visualising sub-surface data associated with drilling operations. Examples can be found in EP07121940.6, U.S. Pat. No. 6,885,942, U.S. Pat. No. 6,917,360, US20030043170, US20040204855, US20050216197 and U.S. Pat. No. 7,027,925. This latter case also discloses animating the images such that dynamic behaviour can be examined. Other examples can be found using combinations of tools and measurements such as bed boundary mappers (e.g. PeriScope from Schlumberger) and real-time data processing, geosteering modelling, and interpretation software (e.g. RTGS Real-Time GeoSteering, and Petrel, both from Schlumberger). One such example is described in the case study: Well Section Placed Precisely in Thin, Heavy Oil Reservoir (2008).
During a well placement operation involving a complex defined trajectory, the drilling equipment including a bottom hole assembly, including a set of logging tools with various sensors, is set up and starts drilling a new well according to a drilling plan. Such operation is today largely conducted in a blind manner with no direct knowledge of the formation ahead of the drill bit. The users, i.e. the driller on the rig, and possibly a well placement engineer and other stakeholders in a remote location, use information from various systems and under different formats: digital data, paper datasheets, 2D drawings of existing wells and surrounding formation, etc. to mentally reconstruct their understanding of what is going on downhole in terms of events and respective positions of the various objects involved (i.e. equipment, well(s), reservoir, formation).
All of the above cases rely on images of a well that has been drilled and so are after the fact. This invention recognises that imaging of the drilling process is most useful where it can be used in the control of the drilling process.